Hi! i have made a hiv test 8 months ago and it was negative 0.195. but i did another one today and the result was neagtive the value was 0.505.why ?

Normal variability: Unfortunately, all the tests we have available today have their limitation and there is usually an acceptable range of variability. It is not likely to get the exact number on two different tests even using the same equipment etc...So, if the results fall in a "range of negative" twice (despite differences), the chance of truly negative is good here. If u r still concerned, consult doc. Good luck.

Limits to Levels: These tests are designed to detect levels of antibody/antigen. Every test is subject to variability as the specimen can vary as can the reagents used for the test. Other viral illness and even allergies can affect the test result levels. If a value changes between screens and risky behavior has occurred a different confirmatory test should be done, not the same test. The value is meaningless.